Inboard-outboard marine drive units present particularly difficult marine steering problems. Inboard-outboard marine drives, of course, are those having an outboard propellor assembly (with all the related drive train gearing, etc.), an inboard engine adjacent to the boat transom, a drive train through the transom between the engine and propellor assembly, and some kind of apparatus for changing the directional orientation of the outboard propellor assembly for purposes of steering.
A variety of steering control apparatuses have been developed for such units, including steering apparatus using cables (with all the related necessary paraphernalia), certain hydraulic apparatus with cylinders and control linkages mounted in various positions to carry out the necessary steering functions, and various other power-steering arrangements. Considerable development efforts have been made toward solving inboard-outboard steering control problems, but difficult problems and disadvantages remain in the field of steering of boats using inboard-outboard drives.
Inboard-outboard steering apparatus problems are particularly difficult in pontoon and houseboat applications, and for other boats having confined areas near their transoms. It is believed that inadequate steering arrangements have limited the number of sterndrive pontoon boats and the like which have been introduced into the marketplace.
In boats having inboard-outboard drive units of various kinds, it is typically desirable to conserve space within the boat, and thus desirable to have the engine close to the transom and to minimize the size of the engine compartment. Among the problems associated with typical inboard-outboard steering devices has been the inherent limitations imposed on boat designers who seek to accommodate steering systems to engine compartments of limited size. As a result, there have been shortcomings in steering apparatus and a lack of adequate mounting systems for steering apparatus.
Due to the typically restricted size of engine compartments in such boats, in some cases designers have had to construct separate cable boxes near the engine compartments, which necessarily take up additional floor space. Furthermore, designers have been required to exercise particular care in routing cables to avoid sharp bends and the like in an effort to ensure that cables have adequate room for free movement, in order that the cable itself does not impede steering or cause steering lock-ups. Cable steering systems can also give rise to potential leakage problems because of various holes typically required for cable systems.
Hydraulic steering systems have been developed and used for pontoons and houseboats and other boats with inboard-outboard drives, and can eliminate some of the above-noted concerns and limitations associated with cable systems. Examples of prior hydraulic steering devices for inboard-outboard drives are disclosed in U.S. Pat. Nos. 4,295,833, 4,557,695, 4,645,463 and 5,340,341.
In the field of hydraulic steering apparatus for inboard-outboard marine drive, there are continuing problems, however, relating to difficulty in installation, use of excessive space, lack of ready understandability, and/or difficulty in serviceability. The marine industry continues to recognize the need for steering systems which are easily installed, take little space, are readily understood and easily serviceable.